Southern blotting analyses of strains of Campylobacter fetus using the conserved region of sapA

Chromosomal DNA of 27 strains of Campylobacter fetus was analyzed by Southern blotting with a probe of the conserved region of sapA. The probe hybridized with 23 strains that produced type A lipopolysaccharide. These strains had more than six sapA homologs. In Southern blots of SalI-digested chromosomal DNA separated by pulsed-field gel electrophoresis, one fragment from 19 strains and two fragments from 4 strains hybridized. These data indicate that multiple sapA homologs are localized to a limited region on the chromosomal DNA of C. fetus and thus suggest the possibility of developing a typing system using this method.